1. Field of the Invention
The present invention relates to a guide mechanism for guiding a pickup head, and particularly to a guide mechanism for guiding a pickup head with respect to an information disk such as an optical disk loaded into a reproducing and/or recording device such as an optical disk drive.
2. Description of Prior Art
Conventionally, an optical disk recording and/or reproducing device includes a loader for loading and ejecting disks, a turntable for rotating loaded disks, a pickup head which generates a laser beam perpendicularly radiating to a loaded disk for reproducing signals from the disk or recording signals onto the disk, and a feeding apparatus for moving the pickup head back and forth along a predetermined radial path of the loaded disk. Common optical disks used include CD-RW (compact disk-rewritable) disks and CD-ROM (compact disk-read only memory) disks. The feeding apparatus includes a driving system for generating a driving force applied to the pickup head, and a guide apparatus for enabling the pickup head to move along the radial path of the loaded disk.
The guide apparatus includes two parallel guide rods that define the path of movement of the optical pickup head, and four fixing seats mounted on a base of the recording and/or reproducing device for connecting the two guide rods with the base. Each fixing seat has a groove therein to receive and fasten the end of a corresponding guide rod, with a fixture screw being engaged with the fixing seat in order to further secure the fastening of the end of the guide rod. The pickup head is hung between the two guide rods. This kind of guide apparatus is described in P.R. China patent no. 01219230.
The rapid advancement of multimedia applications has spawned systems that store information more compactly. In particular, the distance between adjacent recording pits of a modem optical disk is less than previously. This in turn requires that the laser beam generated by the pickup head perpendicularly radiates into the desired pit when recording or reproducing signals to or from disks. Thus the guide rods should be precisely parallel to the optical disk and at exactly the same height above the optical disk. However, each end of each guide rod is directly fastened on the bottom surface of the corresponding fixing seat. The bottom surface may not be completely smooth or may in other respects be uneven because of machining tolerances. This means that the guide rods may not be perfectly horizontal or may be located at different heights. If so, the laser beam transmitted by the optical pickup head slantingly radiates into the desired pit and is liable to fail to properly read/write information from/to the disk.
For these reasons, many manufacturers have been developing adjustable guide apparatuses, in which the positions of the guide rods are changeable. An adjustment device is provided in the guide apparatus. An operator can manually adjust the adjustment device with the help of a testing machine, so as to position the guide rods in the desired locations. However, problems remain. For example, when the guide apparatus is fixed in the testing machine, it is inconvenient for the operator to access the adjustment device and adjust the positions of the guide rods manually. This retards the speed, accuracy and efficiency of production.